Fixing serious memory allocation bug in sbus_message_handler.

dbus_message_append_args() adds a reference to memory that is not
copied to the outgoing message until dbus_connection_send() is
called. Since we compile our reply messages in functions and then
return the reply, we need a mechanism for deleting allocated
memory after invoking dbus_connection_send. I have changed the
arguments to sbus_msg_handler_fn so that it takes a talloc ctx
containing the sbus_message_handler_ctx and a pointer to a reply
object. We can now allocate memory as a child of the reply context
and free it after calling dbus_connection_send.

1 files changed, 8 insertions, 12 deletions

diff --git a/server/polkit/sssd_polkit.c b/server/polkit/sssd_polkit.c
index 6c7d0e1e8..9eda53734 100644
--- a/server/polkit/sssd_polkit.c
+++ b/server/polkit/sssd_polkit.c
@@ -35,17 +35,16 @@ struct spk_ctx {
     struct sbus_srv_ctx *sbus_srv;
 };
 
-static int service_identity(DBusMessage *message, void *data, DBusMessage **r)
+static int service_identity(DBusMessage *message, struct sbus_message_ctx *reply)
 {
     dbus_uint16_t version = POLKIT_VERSION;
     const char *name = POLKIT_SERVICE_NAME;
-    DBusMessage *reply;
     dbus_bool_t ret;
 
     DEBUG(4, ("Sending identity data [%s,%d]\n", name, version));
 
-    reply = dbus_message_new_method_return(message);
-    ret = dbus_message_append_args(reply,
+    reply->reply_message = dbus_message_new_method_return(message);
+    ret = dbus_message_append_args(reply->reply_message,
                                    DBUS_TYPE_STRING, &name,
                                    DBUS_TYPE_UINT16, &version,
                                    DBUS_TYPE_INVALID);
@@ -53,33 +52,30 @@ static int service_identity(DBusMessage *message, void *data, DBusMessage **r)
         return EIO;
     }
 
-    *r = reply;
     return EOK;
 }
 
-static int service_pong(DBusMessage *message, void *data, DBusMessage **r)
+static int service_pong(DBusMessage *message, struct sbus_message_ctx *reply)
 {
-    DBusMessage *reply;
     dbus_bool_t ret;
 
-    reply = dbus_message_new_method_return(message);
-    ret = dbus_message_append_args(reply, DBUS_TYPE_INVALID);
+    reply->reply_message = dbus_message_new_method_return(message);
+    ret = dbus_message_append_args(reply->reply_message, DBUS_TYPE_INVALID);
     if (!ret) {
         return EIO;
     }
 
-    *r = reply;
     return EOK;
 }
 
-static int service_reload(DBusMessage *message, void *data, DBusMessage **r) {
+static int service_reload(DBusMessage *message, struct sbus_message_ctx *reply) {
     /* Monitor calls this function when we need to reload
      * our configuration information. Perform whatever steps
      * are needed to update the configuration objects.
      */
 
     /* Send an empty reply to acknowledge receipt */
-    return service_pong(message, data, r);
+    return service_pong(message, reply);
 }
 
 struct sbus_method mon_sbus_methods[] = {